I am using a WCK plugin to Wordpress. In the php code to call the image source, I used `wp_get_attachment_image_src()` but it only gets the url of the image. I want to include the alt value of it. Please help. Thanks.

Below is my code.

    <div class="authortest-cont">
    				<h2><span>W</span>hat Our <small>Authors Say</small></h2>
    				<?php
    				$wck_custom = get_post_meta( $post->ID, 'testimonialsbox', true);
    				foreach($wck_custom as $wck_cstm) {
    					
    					$author_name = $wck_cstm['author_name'];							
    					$author_img = $wck_cstm['author_img'];
    					$author_testimonial = $wck_cstm['author_testimonial'];
    					
    					if( is_numeric( $author_img ) ) {
    						$attach_author_img = wp_get_attachment_image_src( $author_img, 'full' );
    						$src_author_img = $attach_author_img[0];
    					}
    					else {
    						$src_author_img = $author_img;
    					}
    										
    				?>
    				
    					
    				<div class="col-md-6 col-sm-6">
    					<?php echo $author_testimonial; ?>
    					<div class="author-det">
    						<img src="<?php echo $src_author_img; ?>" alt=""/>
    					</div>
    				</div>
    
    				<?php } ?>
    			</div>

How `echo` alt value of that image?