Using Prims algorithm we start from one vertex and find minimum weight edge vertex adjacent to it and mark it as visited and join them without creating any cycle.
Here starting from point P : adjacent edge weights are PQ(4), PH(5), PR(6).
minimum among them is PQ(4) therefore PQ will be joined so 4-----(1) all options
From point P :adjacent edge weights are PH(5), PR(6)
From point Q: adjacent edge weight are QU(2), QH(3)
minimum among them is QU(2) therefore QU will be joined so 2------(2) option A, B will be considered
From point P:adjacent edge weights are PH(5), PR(6)
From point Q: adjacent edge weight is QH(3)
From point U:adjacent edge weights are UH(1), UT(10)
minimum among them is UH(2) therefore UH will be joined so 1------(3) option A, B will be considered
From point P:adjacent edge weights are PH(5)-not taken as it will form cycle, PR(6)
From point Q: adjacent edge weight is QH(3)-not taken as it will form cycle
From point U:adjacent edge weights is UT(10)
From point H:adjacent edge weights are HR(7), HT(9)
minimum among them is PR(6) therefore PR will be joined so 6------(4) option B will be considered
From point P:adjacent edge weights is PH(5)-not taken as it will form cycle
From point Q: adjacent edge weight is QH(3)-not taken as it will form cycle
From point U:adjacent edge weights is UT(10)
From point H:adjacent edge weights are HR(7)-not taken as it will form cycle, HT(9)
From point R:adjacent edge weights is RT(8)
minimum among them is RT(8) therefore RT will be joined so 8------(5) option B will be considered
Finally option B is correct with sequence 4,2,1,6,8