如图所示,用弹簧测力计拉着木块在水平桌面上作直线运动,实验记录如表.由此可知,木块与水平桌面的滑动摩擦力为( )

A.4.5N
B.1.5N
C.3N
D.2.1N
0 105731 105739 105745 105749 105755 105757 105761 105767 105769 105775 105781 105785 105787 105791 105797 105799 105805 105809 105811 105815 105817 105821 105823 105825 105826 105827 105829 105830 105831 105833 105835 105839 105841 105845 105847 105851 105857 105859 105865 105869 105871 105875 105881 105887 105889 105895 105899 105901 105907 105911 105917 105925 235360
| 实验次数 | 1 | 2 | 3 |
| 木块运动情况 | 越来越快 | 越来越快 | 越来越慢 |
| 弹簧测力计示数/N | 4.5 | 4.5 | 2.1 |
A.4.5N
B.1.5N
C.3N
D.2.1N