What is one of the primary duties of the lead who plays first in an end?

The primary duty of the lead who plays first in an end is to place the mat. This action is crucial as it establishes where the play begins for that end. The lead is responsible for determining the starting point of the game by positioning the mat, which ensures that all players adhere to the same standard of play for that end. Placing the mat accurately is essential, as it affects the distance from which the players will deliver their bowls.

While the other options involve responsibilities related to the game, they are not part of the lead's primary duties. Delivering the last bowl usually falls under the responsibilities of the skip or last player, counting the shots is typically done by the skip or players after all bowls have been delivered, and determining the winner of the end is also not the lead's responsibility but rather a collaborative task based on the outcome of the bowls placed. Thus, placing the mat stands out as the key responsibility of the lead at the start of an end.