349. To adjust the amount of safety valve blow down, as shown in the illustration, you would reposition the part indicated by arrow '_______

Blowdown is adjusted by repositioning the blowdown ring, which is indicated by arrow B. This ring controls the pressure drop between the valve's opening and reseating pressures by altering the huddling chamber's geometry, without affecting the set pressure. Options A, C, and D involve components that adjust set pressure or test operation, not blowdown.