You must redistribute only /24 prefixes inside 10.0.0.0/8 into BGP. Which configuration accomplishes this?

The correct option uses an IP prefix-list with ge 24 le 24 to precisely match only /24 prefixes within the 10.0.0.0/8 range. This prefix-list is then referenced by a route-map, which is applied to the BGP redistribution process. This is the standard and most effective method for granular prefix length filtering during redistribution into BGP. Applying a distribute-list under BGP to filter outbound updates by prefix length is incorrect because distribute-lists primarily filter based on IP addresses, not directly on prefix lengths in the same flexible way a prefix-list can. Using a standard access-list matching 10.0.0.0 0.255.255.255 on the redistribute command is insufficient as standard access-lists match only the network address, not the prefix length, and would permit all prefixes within 10.0.0.0/8, not just /24s. Configuring a null route for undesired prefixes and redistributing the remaining networks is an inefficient and indirect method for filtering specific prefix lengths during redistribution and is not the intended use of null routes for this purpose.