Knockout eg

HTML

<script src="//code.jquery.com/jquery-3.3.1.slim.min.js"></script>
<link rel="stylesheet" href="//stackpath.bootstrapcdn.com/bootstrap/4.1.0/css/bootstrap.min.css">
<script src="//cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.0/umd/popper.min.js"></script>
<script src="//stackpath.bootstrapcdn.com/bootstrap/4.1.0/js/bootstrap.min.js"></script>
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css">
<div class="row">
        <div class="col-sm-12">
            <table class="table table-bordered table-striped">
                <thead>
                    <tr>
                        <th>Roll No</th>
                        <th>Sex</th>
                        <th>Uniform type</th>
                    </tr>
                </thead>
                <tbody data-bind="foreach:studentData">
                    <tr>
                        <td><span data-bind="text:rollNo"></span></td>
                        <td><select class="form-control" data-bind="options:$parent.sexDropDown,optionsText:'name',optionValue:'id',value:sex,optionsCaption:'-Select-'"></select></td>
                        <td><select class="form-control" data-bind="options:$parent.uniformTypeDropDown,optionsText:'name',optionValue:'id',value:uniform,enable:sex() ? (sex().id == 2):false,optionsCaption:'-Select-'"></select></td>
                    </tr>
                </tbody>
            </table>
        </div>
    </div>

JavaScript

var studentViewModel = function () {
	self = this;
  
  
  self.studentData  = ko.observableArray([
		{ rollNo: 1, sex: ko.observable(null), uniform: null },
		{ rollNo: 2, sex: ko.observable(null), uniform: null },
    { rollNo: 3, sex: ko.observable(null), uniform: null }
	]);
  
  self.sexDropDown  = ko.observableArray([
		{ name:"Male", id: 1 },
		{ name:"Female", id: 2 }
	]);
  
  self.uniformTypeDropDown  = ko.observableArray([
		{ name:"Skirt", id: 1 },
		{ name:"Trousers", id: 2 },
    { name:"Salwar", id: 3 }
	]);
  };

var viewModel = new studentViewModel();

ko.applyBindings(viewModel);