Final answer:
A barbarian's Reckless Attack ability gives them advantage on melee weapon attack rolls, meaning they roll two d20s and choose the higher roll for attacks. However, attackers also get advantage on attack rolls against the barbarian until their next turn. Option B is the correct description of this ability.
Step-by-step explanation:
The barbarian's Reckless Attack ability refers to a special feature in the role-playing game Dungeons & Dragons. This ability specifically allows barbarians to gain an advantage on their melee weapon attack rolls during their turn. However, there is a trade-off for using Reckless Attack, as it also gives attack rolls against the barbarian an advantage until the barbarian's next turn. This can represent the barbarian throwing caution to the wind to land powerful blows but at the risk of taking more hits from enemies.
Option B correctly describes the Reckless Attack ability: Barbarians gain advantage on their melee weapon attack rolls. This means that when a barbarian opts to use this ability on their turn, they can roll two d20s and use the higher roll for their attack, which can significantly increase the likelihood of a hit. This ability does not allow for sneak attacks, multiple attacks in a single turn, or the use of ranged weapons without disadvantage in close combat, which eliminates options A, C, and D.