This is true ,
Ensures that only a part of the Visualforce page is refreshed, developers can use the reRender attribute of the <apex:commandButton> tag. This attribute specifies the IDs of the components that should be re-rendered as a result of the action method being completed. In this case, setting the reRender attribute to the ID of the <apex:pageBlockSection> that contains the opportunity list will cause only that section to be updated on the page, resulting in a partial page refresh.
The correct answer is B because it uses the reRender attribute correctly to update only the specific part of the page (opportunityList) without a full page refresh.
References:
https://developer.salesforce.com/docs/atlas.en-us.pages.meta/pages/pages_compref_commandButton.htm

Ex:
<apex:page controller="OpportunityListController">
<apex:form>
<!-- Section for the command button -->
<apex:commandButton value="Refresh Opportunities" action="{!loadOpportunities}" reRender="opportunitySection" />
<!-- Opportunity list section that will be refreshed -->
<apex:pageBlock title="Opportunity List">
<apex:pageBlockSection id="opportunitySection" columns="1">
<apex:repeat value="{!opportunities}" var="opp">
<apex:outputText value="Name: {!opp.Name}" /><br/>
<apex:outputText value="Stage: {!opp.StageName}" /><br/>
<apex:outputText value="Close Date: {!opp.CloseDate}" /><br/>
<br/>
</apex:repeat>
</apex:pageBlockSection>
</apex:pageBlock>
</apex:form>
</apex:page>...